Fuel injection system anti-siphon device



Dec. 6, 1960 R. w. RICHARDSON FUEL INJECTION SYSTEM ANTI-SIPHON DEVICE 2Sheets-Sheet 1 Filed Nov. 3, 1958 Dec. 6, 1960 R. w. RICHARDSON FUELINJECTION SYSTEM ANTI-SIPHON DEVICE 2 Sheets-Sheet 2 Filed Nov. 3, 1958FUEL INJECTION SYSTEM ANII-SIPHON DEVICE Robert W. Richardson,Birmingham, Mich, assignor to General Motors Corporation, Detroit,Mich., a corporation of Delaware Filed No 3, 1958, Ser. No. 771,575

4 Claims. (Cl. 261-38) The present invention relates to an anti-siphondevice adapted particularly for use with a fuel injection system of thetype shown in Serial No. 591,889, Dolza, filed lune 18, 1956. In theaforenoted fuel injection system the individual cylinder nozzles arelocated below the main fuel metering mechanism as a consequence of whichthere is a tendency to set up a siphoning action through the nozzles asa result of which the fuel continues to flow draining the fuel linesafter the system has been shut off.

Various mechanisms have been provided in the past to overcome thisdifliculty. While several of these devices have performed satisfactorilythey have had many disadvantages including those of cost andcomplication. In addition, where siphoning has been prevented by the useof a relatively heavy weighted member that is moved by fuel flow andadapted to block the fuel passage due to gravity when such flow Wasstopped, a serious calibration problem was created which is overcome bythe present simplified anti-siphoning device.

In the present device a siphon break passage is provided and includes apair of upwardly inclined legs and a light ball check valve disposed atthe juncture of these legs. The check valve is normally raised to blockan atmospheric vent passage when fuel is flowing from the fuel supplypump to the fuel metering valve. The ball check valve being extremelylight provides no problem of calibration. On the other hand, when fuelflow ceases the ball check valve drops communicating the anti-siphonpassage at atmosphere and thereby interrupting any tend ency towardsiphoning.

Further details as well as other objects and advantages will be apparentfrom a perusal of the detailed description which follows.

In the drawings:

Figure 1 represents a fuel injection system embodying the subjectinvention;

Figure 2 is a partial plan view of Figure 1;

Figure 3 is a view along line 33 of Figure 2;

Figure 4 is an enlargement of the ball check vent valve; and

Figure 5 is a view along line 5-5 of Figure 4.

The fuel injection system is housed in a casing indicated generally at10. Save insofar as will be specifically pointed out hereinafter, thefuel injection system does not, per se, constitute a part of the presentinvention. A fuel pump 12 is adapted to supply fuel under pressure to afuel metering valve indicated generally at 14. The operation of the fuelmetering valve is set forth in detail in the aforenoted Dolzaapplication. Briefly, however, it might be noted that the fuel meteringvalve in the subject system is controlled in accordance with mass airflow as measured through venturi and which valve is adapted to supplyincreased quantities of fuel to nozzles 16 as such air flow increases.Each nozzle 16 is supplied with fuel from a conduit 18 leading from adistributor 20 which is supplied from metering valve 14 by conduit 22.

rates atent It is to be noted that nozzles 16 are located below the fuelmetering system casing 10 and hence below pump 12. As a consequence,there is a tendency for the nozzles to siphon the fuel out of lines 18and 22 in which case fuel will continue to flow and drain the systemafter the engine has been shut otf. To prevent this occurrence ananti-siphon passage is provided between pump 12 and metering valve 14.The anti-siphon passage includes a pair of upwardly inclined legs 24 and26 formed in casing 10. A chamber 28 is formed at the juncture of legs24 and 26. Thus, fuel in being delivered from pump 12 to metering valve14 must flow through leg passages 24 and 26 and in so doing pass throughchamber 28. The upper side of chamber 28 opens to atmosphere.

A valve body 30 having an opening 32 therethrough is disposed inatmospheric vent chamber 28. Seat passage 32 is enlarged at 34 toreceive a light ball check valve 36. The lower end of valve body 30 iscrimped or otherwise formed to provide supporting fingers 38 to retainvalve 36 within passage enlargement 34. As best seen in Figure 5, thelower end 40 of passage 32 is sufliciently larger than ball valve 36that even with the latter seated on fingers 38 air may flow therearoundand communicate with passages 24 and 26. A seat 42 is formed at theupper end of body 30. Thus when fuel is forced to flow through passages24 and 26 the pressure thereof will act against ball check valve 36causing the same to move against seat 42 and preventing fuel fromdischarging out of vent passage 32. When, on the other hand, pump 12ceases to pump fuel through passages 24 and 26, the drop in fuelpressure will permit ball check valve 36 to drop under the influence ofgravity and atmospheric pressure against fingers 38 thereby uncoveringseat 42 in valve body 30 and permitting air under atmospheric pressureto pass valve 36. Thus any tendency of the fuel in passages 24 and 26 aswell as in conduits 18 and 22 to continue to flow after the system hasbeen shut off is interrupted by the opening of the atmospheric vent.

By preventing siphoning of the fuel lines, the latter remain chargedwith fuel in order that the system may begin to function quickly tosupply fuel to the engines cylinders when the system is again madeoperative. In addition flooding of the manifold with fuel is eliminated.

I claim:

1. A charge forming device for an internal combustion engine comprisingmeans for supplying metered quantities of .fuel to the engine, a sourceof fuel under pressure, passage means communicating said fuel sourcewith said metering means, nozzle means disposed vertically below saidmetering means and said fuel source, and conduit means communicatingsaid metering means with said nozzle means, said passage means includingat least a portion disposed vertically above said metering means andsaid fuel source means, said passage portion communicating with anatmospheric passage, and a ball check valve member disposed within saidportion and normally seated by the fuel under pressure in said passagemeans to block said atmospheric passage, said ball check valve beingadapted to open under the influence of gravity and atmospheric pressurewhen the pressure in said fuel passage drops below a predetermined valueto admit atmospheric air to said passage.

2. A charge forming device as set forth in claim 1 in which said passagemeans comprises a pair of inclined passages which intersect at a pointvertically above the fuel source and metering means and a passageextending upwardly from said point of intersection to communicate withthe atmosphere.

3. A charge forming device as set forth in claim 2 in which a valve bodyis disposed Within said upwardly extending passage, a passage withinsaid body adapted tocommunicate the passage means with atmosphere, and aball valve disposed within said body passage, fuel flow through thepassage means induced by the fuel pressure source seating the valve toblock communication of the passage means with the atmosphere, said valvecommunicating atmosphere to the passage means when said source isinoperative to supply fuel under pressure.

4. A charge forming device as set forth in claim 3 in which said valvebody passage extends longitudinally of the body, said passage includingan enlarged section intermediate its ends, said ball valve member beingdisposed within said section, aseat formed in said passage, said valvemember being adapted to coact with said seat to block admission ofatmospheric air to the passage, and a pair of radial fingers adapted toretain said valve within said section.

No references cited.

